REACTION OF 1,4-DIBROMO-2,3-DIHYDROXYNAPHTHALENE WITH 2-NAPHTHOXIDE ION - SOLVENT AND CATION CONTROL IN THE FORMATION OF THE CONFORMATIONALLY LOCKED STEREOISOMERS OF 2,2',3',2'-TETRAHYDROXY-1,1' 4',1''-TERNAPHTHYL AND ',2''-HEXAHYDROXY-1,1'/4',1'',1'''-QUATERNAPHTHYL/

The reaction of the dibromide 1 with the 2-naphthoxide ion 2 proceeds under remarkably mild conditions (25-50 degrees C), yielding all possi ble stereoisomers of ternaphthol 3 and quaternaphthol 4. An unambiguou s structure assignment has been made for the individual stereoisomers and conditions for their thermal interconversion have been established . In contrast to a nonselective distribution of stereoisomers found in the thermodynamic equilibrium mixture, a high stereoselectivity can b e induced in the coupling reaction under kinetic control. The coordina ting ability of the alkali metal counterion (M(+)) of the participatin g 2-naphthoxide ion 2 has been found to play a key role in the stereoc ontrol, supporting strongly the formation of the cis stereoisomers of 3 and 4. When the coordinating ability of M(+) is suppressed by an eff icient solvation and/or by complexation with 18-crown-6, formation of the traits stereoisomers prevails in the reaction.